They are my uncle's children.
cousins
He is my aunt's husband.
uncle
He is my son's son.
grandson
They are my son's children.
grandchildren
He is my father's father.
grandfather
She is my uncle's wife.
aunt
She is my son's daughter.
granddaughter
She is my mother's mother.
grandmother
They are my father's parents.
grandparents
She's my father's sister.
aunt
He's my mother's brother.
uncle